Abnormal bleeding, feeling really worried:(

I've been bleeding since the 5th August. It was heavy to start and now has tapered off to a light spotting. I've also got mild cramping.

I had a mirena coil fitted 14 months ago and have not specifically stopped having periods- light flows on and off. It's been annoying as I never knew when it was coming but this particular episode is scaring the hell out of me because it seems there is no end in sight, plus I needed tampons for most of this time. The reason I'm so scared is because I had cervical abnormalities (CIN 3) 10 years ago and although my smears have been clear since, I'm terrified its back.

I'm booked to see my doc tonight. Can anyone relate to this or have any words of advice?